Sexual activities and oestrus detection in lactating Holstein cows

During 6 weeks, the oestrus behaviour of all non-pregnant cows on two dairy farms was observed for periods lasting 30 min at 2 h intervals. Cows were housed in a free stall with cubicles and a concrete slatted floor. Pedometers were used to measure the physical activity of the cows throughout the oestrous cycle. Milk progesterone levels were used for confirmation of the oestrus date. Overall oestrus behaviour was less intense than described in previous studies. In only 37% of the oestruses was a standing heat observed. The behavioural oestrus symptoms were seen more frequently during the nocturnal period. Duration and intensity of the oestrus behaviour were influenced by the number of cows in oestrus. Pedometer readings were correlated with mounting other cows, resting with the chin on other cows, and total oestrus behaviour score. Two observations of 30 min per day would result in a detection efficiency of 74% and an accuracy of 100%. The time of observation during the day was found to be very important. Observations before milking gave a lower detection rate than observations after milking and feeding.